rubdawg said:Yah, an anechoic chamber I have used and it is quite expensive. This is mainly needed for cell phone use so it would have to cover at least 800MHz to 3GHz(UMTS/WIFI now in phones)any one day and saw that they had a box the size of a regular office desk and used that to measure antenna perfromance, mainly it was a near-field measurement, and i know that it was homemade type, but that was about 3 years ago and not intereste in antenna, but now it is my line of work.
biff44 said:Want one for almost free? Go test the antenna outside. You can set up to keep all the expensive equipment indoors, and just get a pair of antenna rotators from a local ham shack (get a digital indicator/control) to mount on a wooden pole, and put another pole or two for the destination antenna. You can make all sorts of antenna pattern tests. I did some antenna testing that way, and got very usable results.
Won't be that good for EMI testing, though.
The problems with building an anechoic chamber are two. First, usually people want them EMI tight, so all the surfaces have to be conductive. But, you do not want re-radiation from those conductive surfaces, so you then have to cover every surface with very expensive blocks of RF absorber. If you are only going to work at one frequency, you could probably get away with just a thin sheet of absorber engineered to absorb that one frequency, but usually you want some bandwidth to the room.
Most testing defines the need for a ground plane, and the outside earth serves as a good one for free.
tnx, it was fasthowever, I want to use it inside our chamber, not out side. Do you know what is their rotary resolution? Can I use something like AR-35, or it's not precise enough? What about dish rotators? too many questions! last one: i prefer to use a non-metallic system, it'll add to the chamber reflections. is there any plastci one out there?
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